Union leaders for US Airways mechanics and ground workers met with American Airlines management and federal mediators this week in Washington, D.C., but made no significant progress on contract talks.

After the meetings, held at National Mediation Board offices, the International Association of Machinists reiterated its request to be released from talks and to have an impasse declared. The two sides have been in contract talks since 2011.

“US Airways’ refusal to settle fair contracts that provide comparable wage rates to what it negotiated with American’s employees who perform the same work is an insult,” IAM District 141 President Rich Delaney said. “We demand a release from these fruitless discussions so we can exercise our right to strike.”

Before an airline union can consider a strike against its employer, it must first ask for “release” from negotiations from federal mediators. A 30-day cooling-off period begins before a union can take any stop-work action.

American, which merged with US Airways in December, said it wants to negotiate new joint contracts with all its unions as the carriers integrate.

“Based on the meetings, we expect the NMB to schedule additional sessions to continue our discussions,” the company said in a statement.

Earlier this week, the president of the Transport Workers Union, which represents mechanics and ground workers at American, said he supports the IAM’s efforts to seek permission from federal mediators to strike at US Airways.

“This is supposed to be the new and better American,” TWU International President Harry Lombardo said. “Management has said they want to have better labor relations than existed at either US Airways or the old American.

“Yet the airline’s leadership has locked mechanics and other ground workers represented by IAM into a second-class status where they get lower pay and fewer benefits than workers represented by TWU for the same work at the same airline.”

The last time the National Mediation Board released an airline union from talks was in 2010 when it allowed Spirit Airlines pilots to strike. They held a six-day strike before reaching a contract agreement with the low-cost carrier.